A time-interleaved analog to digital converter (ADC) includes capacitor array circuits, a flash ADC, first and second circuits, a converter, and an encoder circuit. The capacitor array circuits sample an input signal and generate first residue signals according to first quantization signals. The flash ADC samples the input signal and generates the first quantization signals. The first circuits transfer the first residue signals from the capacitor array circuits. The converter performs a signal conversion according to the first and the second residue signals to generate a second quantization signal. The second circuits transfer second residue signals to the converter. The capacitor array circuits further generate the second residue signal in response to the signal conversion. The encoder circuit generates a digital output according to one of the first quantization signals and the second quantization signals.